Resistant pests cause farmers excessive stress and costly crop losses each year. Rotating modes of action maximizes insect control and minimizes resistance development, improving growers’ bottom lines.
“Many insect pests have a high propensity to develop resistance, including the diamondback moth — one of the most difficult pests to control and one of the most important pests when it comes to resistance management. They are adept at surviving, making them the most problematic pests over multiple crops and multiple generations,” said Shine Taylor, North America Biology Leader Insecticides, Corteva Agriscience™, Agriculture Division of DowDuPont.
Before each season, growers should review their integrated pest management (IPM) program to ensure they are rotating out of the mode of action used previously. Switching between brand names may not be enough — many brands use the same mode of action, potentially increasing resistance development. For example, multiple insecticide sprays of a singular mode of action, such as diamide, can limit pest control, both now and in future years, due to resistance development.
Spinetoram, the unique active ingredient in Delegate® WG insecticide, is alone in a chemical class (Group 5), making it essential to resistance management. Targeting pests by contact and ingestion, Delegate quickly knocks down insects, saving growers the costly habit of nonstop spraying.
Even if you know the active ingredient of a product, read the label to determine the Insecticide Resistance Action Committee (IRAC) class of insecticide and ensure you are rotating mode of action, Taylor recommended.
“Trade names make things very complicated for growers, consultants and retailers because the mode of action isn’t always easily discernible,” he said. “This is especially true for diamide-containing insecticides, which may be sold under several different trade names, all with different mixtures and multiple active ingredients.”
Taylor points to the IRAC website as an exhaustive reference to educate about modes of action for resistance management planning.
“Diamides are classified a Group 28 insecticide, and it’s important to avoid using another Group 28 product during that application window or season based on your resistance management strategy. In comparison, Delegate WG insecticide is a Group 5 insecticide. Ideally, growers should rotate between not just trade names but also modes of actions,” Taylor said.
Additionally, insecticide premixes that include two modes of action can affect resistance management plans.
“Target pests with the mode of action required for control, because spraying unnecessary products could speed up resistance development,” he said. “With a premixed product, you may only need one of the active ingredients and could potentially be flaring another pest with the second active ingredient. It is also important to remember that while there are some great products that when mixed together improve control, you are using up multiple modes of action in one treatment.”
Continuously rotating modes of actions minimizes resistance development.
“Resistance development can ultimately cause manufacturers to pull a product from the market, and we could potentially lose that active ingredient from our arsenal. We might even lose efficacy to neighboring chemistries if cross-resistance develops,” he said. “Rotating modes of action avoids selectively breeding a pest population with tolerance or resistance that carries over to multiple generations.”
Delegate offers growers an ideal partner in season-long insect control programs. Delegate offers a novel mode of action for fast knockdown and lasting control of a broad spectrum of destructive pests, such as Oriental fruit moth, leafminers, numerous worms, leafrollers, thrips and spotted wing drosophila.
“Rotating Delegate, with spinetoram as an active ingredient, with another product containing another mode of action will, over the long term, lengthen the efficacy of each mode of action,” Taylor said.
Delegate® WG insecticide has a short four-hour re-entry interval and is easy on beneficial insects. When applied according to the label, Delegate is nondisruptive to beneficials, has no damaging effect on lady beetles or lacewings and does not cause mite flaring.
“Sometimes it takes some additional planning at the beginning of the year to prepare your season-long resistance management program. Do that math. Choosing the optimum chemistry for each stage of the growing season will leave you additional modes of action in your toolbox,” he said.
On top of rotating modes of action, scouting your fields regularly for pest presence will keep you aware of unsavory visitors and up to date on whether you need to apply additional sprays.
To learn more about how Delegate can help keep orchards free of yield-robbing pests, visit: https://www.corteva.us/products-and-solutions/crop-protection/delegate-wg.html
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